An electrostatic chuck made of ceramic manufactured by sandwiching electrodes between ceramic electrostatic substrates made of alumina and firing them applies an electrostatic suction power to built-in electrodes and sucks a substrate such as a silicon wafer or the like by an electrostatic force. In the electrostatic chuck like this, an inactive gas such as helium (He) or the like is flown between a surface of the ceramic dielectric substrate and a back side of the substrate being a suction object, and a temperature of the substrate being the suction object is controlled.
For example, temperature increase of the substrate may be accompanied during processing in a CVD (Chemical Vapor Deposition) apparatus, a sputtering apparatus, an ion implantation apparatus, an etching apparatus or the like in which the substrate is processed. In the electrostatic chuck used for those apparatus, an inactive gas such as He or the like is flown between the ceramic dielectric substrate and the substrate being the suction object, and the temperature increase of the substrate is suppressed by bringing the inactive gas into contact with the substrate.
In the electrostatic chuck which controls the substrate temperature by the inactive gas such as He or the like, holes (gas introduction path) for introducing the inactive gas such as He or the like are provided in the ceramic dielectric substrate and a base plate supporting the ceramic dielectric substrate. Through holes communicating with the gas introduction path of the base plate are provided in the ceramic dielectric substrate. Thereby, the inactive gas introduced from the gas introduction path of the base plate is introduced to a back side of the substrate through the through holes of the ceramic dielectric substrate.
Here, when processing the substrate in the apparatus, discharge (arc discharge) from the plasma in the apparatus toward the base plate made of a metal may be generated. The gas introduction path of the base plate and the through hole of the ceramic dielectric substrate may be likely to be a path for discharge. Then, there is a technique that resistance (breakdown voltage or the like) to the arc discharge is improved by providing a porous part in the gas introduction path of the base plate and the through hole of the ceramic dielectric substrate. For example, an electrostatic chuck is disclosed, which insulation property in the gas introduction path is improved by providing a ceramic sintered porous body in the gas introduction path and making a ceramic sintered porous body structure and a film pore a gas flow path. An electrostatic chuck is disclosed, which a discharge prevention member made of the ceramic porous body and being a process gas flow path for preventing the discharge is provided in a gas diffusion gap. An electrostatic chuck is disclosed, which a dielectric insert is provided as a porous dielectric such as alumina and the arc discharge is reduced. It is desired that while securing a resistance to the arc discharge and a flow rate of the gas, a mechanical strength (rigidity) of the porous part is improved in the electrostatic chuck including the porous part like this.